ASHRAE STD 62.1
Ventilation for Acceptable Indoor Air Quality
|Publication Date:||27 January 2021|
Addendum a clarifies that air density adjustments are permitted but are not required. At the publication of ANSI/ASHRAE Standard 62.1-2016, General Notes for Table 126.96.36.199, Note 3 was modified from "Air density: Volumetric airflow rates are based on dry air density of 0.075 lbda/ft3 (1.2 kgda/m3) at a barometric pressure of 1 atm (101.3 kPa) and an air temperature of 70°F (21°C). Rates may be adjusted for actual density, but such adjustment is not required for compliance with this standard." to read "Air density: Volumetric airflow rates are based on dry air density of 0.075 lbda/ft3 (1.2 kgda/m3) at a barometric pressure of 1 atm (101.3 kPa) and an air temperature of 70°F (21°C). Rates shall be permitted to be adjusted for actual density." This change was undertaken as editorial in order to conform the standard to standard language requirements but has led to confusion as to whether density adjustments are required. Although the technical basis for ventilation in this standard is rooted in mass balance, the customary means of measuring airflow rates is volumetric. A requirement for density corrections would represent a substantive change and would have implications for other requirements in the standard.
Note: In this addendum, changes to the current standard are indicated in the text by underlining (for additions) and (for deletions) unless the instructions specifically mention some other means of indicating the changes.